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Estimation of Carbon Dioxide Fluxes Between Land, Ocean and Atmosphere During 2006–2011 with a 4D Variational Assimilation Scheme and Special Reference to Asia
No full textThe rates of exchange of carbon dioxide between atmosphere, land and ocean is a key component of the global carbon budget. It is extremely important to quantify these both on a spatial and temporal basis as it can identify sources and sinks of anthropogenic carbon which are important in setting goals for country-wise emissions and uptake. This chapter presents results from a 4D variational assimilation scheme of ingesting carbon dioxide data between 2006 and 2011 into the adjoint of the LMDZ transport model to obtain fluxes between land, ocean and atmosphere. Carbon dioxide data from three stations from India (Hanle, Pondicherry and Port Blair) along with one hundred global stations have been assimilated into the model, and this is expected to increase the confidence in the results for the tropical and temperate Asian regions. The grid point-wise results are aggregated into larger regions representing India, China, USA, Western Europe and the Rest of the World to reflect the quantification of sources and sinks in these regions. In addition, aggregation in terms of Transcom regions is also presented
Numerical Analysis of High Reynolds Number Effects on the Performance of GAW-1 Airfoil
No full textThe aerodynamic behaviour of the GAW-1 airfoil at high Reynolds number is analysed numerically using the Spalart-Allmaras (SA) turbulence model.Initially an inter-code comparison is carried out at Re=6×106 and the aerodynamics characteristics obtained using the in-house flow solution code 3D-PURLES and the open source CFD tools SU2 and OpenFOAM are validated with the available measurement data. Based on this validation exercise, 3D-PURLES is used to study the effect of increasing Reynolds number (1, 3, 6, 9, 12 millions) on the aerodynamic characteristics
Shockwave Oscillations Over the Conical Heat Shield Region of a Typical Launch Vehicle at Mach 0.95
No full textThe occurrence of shock wave over the typical launch vehicle model with conical heat shield at a free-stream Mach number of 0.95 was studied using flow visualization techniques. Both oil flow pattern, as well as shadowgraph image techniques, have been used to trace the flow features over the model. The study was conducted at a various angle of attack from 0∘ to 4∘ in steps of 1∘. Instantaneous shadowgraph images of shock wave pattern over the surface of the conical heat shield region were captured using a highspeed camera. The image shows a series of compression weak waves which forms a standing normal shock wave on the heat shield region at angles of attack of 0∘, 1∘, and 2∘. Further increase in angle of attack, the normal shock wave splits into lambda-shaped shock pattern. At an angle of attack 3∘ and 4∘, shock-induced separation and reattachment process result in shock oscillations along the surface of constant heat shield cylindrical region. The frequency of shock wave oscillations was found to increase with the angle of attack from 3∘ to 4∘. The oil flow pattern clearly evident that the average distance covered during the shock oscillations
Conclusions and Future Work
No full textNeural partial differentiation (NPD) method is used for the parameter estimation. For this purpose initially, a neural model of multi-input and multi-output (MIMO) aircraft system is established. In addition to that, separate consideration of the longitudinal and lateral-directional dynamics simplifies the model considerably in terms of structure and the number of parameters
Experimental evaluation of elastic ring squeeze film dampers for small gas turbine engine
No full textSqueeze film dampers play a vital role in absorbing vibration energy in a rotor bearing system. The damper under study has an elastic ring with pedestals between bearing and stator dividing oil cavity into small oil pockets. This arrangement is different from conventional squeeze film damper where a single annular oil film is formed. This provides the required support stiffness as well as damping to the rotor. These types of dampers are called elastic ring squeeze film dampers (ERSFD) which are mainly used in high-speed small gas turbine engines by virtue of its compact design. There are very few literatures available to evaluate the damping offered by these SFDs. The main objective of this work is to determine the damping offered by ERSFD experimentally. For this study the rotor is designed to simulate the dynamics of a typical gas turbine engine. The rotor has to cross two rigid critical speeds within 18,000 rpm. The rotor response is measured under undamped (UND-without oil supply) and damped (D-with oil supply) conditions to evaluate the damper performance. The performance data is generated at three different oil temperatures (40, 70 and 100 ℃) under unbalanced load ranging from 2 to 8 g at 58.5 mm radius (UBR). This experimentation and performance analysis shows enhanced damping at critical speeds leading to the reduction in rotor vibrations after introducing ERSFD. The experimental data is further processed to calculate the amount of damping offered by ERSFD using rotor dynamic relations
Effect of offshore troughs on the South India erratic summer monsoon rainfall in June 2017
No full textThe onset and advance of southwest monsoon are accompanied by the appearance of the offshore trough along the southwest coast of India. This offshore trough escorts a deluge of rainfall to the southwest coast, and sometimes rainfall band moves eastward further into south India. These broad observations were noticed during the summer monsoon of June 2017. Meteorological agencies and media had reported a huge amount of rainfall over the southwest coast of India during the month. But, in the far interior of south India, rainfall was less. Due to the less rainfall, water resources depleted, which affected local farmers and common man of south India. The confused views of the common man on southwest coast rainfall could be due to lack of understanding related to various factors affecting rainfall over the same region. This article is an endeavor to address the preliminary understanding of the southwest coast rainfall during June 2017, with more stress on offshore troughs. The study begins with area-averaged rainfall statistics over south, southwest, and southeast India by employing satellite and rain gauge merged rainfall datasets. Area averaged analysis revealed offshore trough contributed 80 % of rainfall over the South West India, 68 % over South East India, contributing to an overall 75 % over south India in 2017. To identify offshore trough position and strength in the reanalysis and model simulations, a new method called VSV (Vertical Shear of Vorticity) method was introduced. The computed offshore troughs were categorized into Active, Normal, and Feeble based on the strength of meridional gradient of mean sea level pressure and 850 hPa horizontal winds. The contribution due to each category of the offshore trough over different sub-regions was investigated to find out the effect of the offshore trough to total rainfall. Dynamic and thermodynamic features of these categories of the offshore trough were investigated by using proxies like equivalent potential temperature and moisture flux convergence. We found that during active offshore trough an eastward propagation of rain bands persists, which was explained by using moisture flux convergence and equivalent potential temperature at different levels of the atmosphere
Hard Real-Time Delay (RTD) Estimation and Analysis for Safety-Critical System
No full textAvionics embedded systems encapsulate the greater number of processing units that are completely under its control and with respect to the functional requirement very often they have strict timing analysis. The purpose of this work
is to capture the timing analysis of the system-level data transfer using the AFDX format sending to the Multi-functional display computer, which has an IMA architecture. In the most recent years due to the strong partition of integrated modular avionics (IMA) architecture, they have been widely adopted in the field of avionics. In the development of avionics systems, although the architecture of IMA can achieve an effective reduction in cost and enhancement in reliability it results in less scheduling difficulty. So, even under the worst-case situations the deadlines of the IMA system should be meet and evaluation of the latency period has to obtain. The methodology involved for timing analysis is presented based on the case study carried out using visualsim simulation platform
Trigger mechanism for obtaining dynamic derivatives in wind tunnels using free-oscillation technique
No full textMicrobial fuel cells for a soil-based green energy conversion system
No full textThis paper presents technological aspects, operating principle and scientific applications of microbial fuel cells (MFCs) for a soil-based green energy conversion system. MFC provides a likely low cost, a highly efficient and renewable energy-producing alternative to conventional energy resources. Only a few biosensors MFC have been used practically, providing current for low power devices. To further improve the MFC technology, an understanding of the limitations and microbiology of these systems are required. Some researchers are uncovering that the importance of the MFC technology is not only the production of electricity but the ability of electrode associated microbes to degrade wastes and toxic chemicals. This paper provides a platform to explore the possibilities of generating renewable power using biomass and the working principle of the MFC technology with its applications. The soil microbial fuel cell (SMFC) technology is also implemented in the soil for green electricity generation
Superb catalytic activity of as-green synthesized copper ferrite's thermal decomposition of ammonium perchlorate
No full textA simple one step method is employed for the synthesis of CuFe2O4 nanoparticles (NPs) aided by utilizing egg albumin (EA) and aloe vera (AV) as solvents. The samples were characterized using X-ray diffraction (XRD), Field Emission Scanning Electron Microscopy (FE-SEM), Thermo Gravimetric/Differential Thermal Anaysis (TG/DTA), Vibration Sample Magnetometer (VSM) and X-ray Photolectron Spectroscopy (XPS). XRD analysis of the samples sowed the presence of CuFe2O4 and CuO in the samples. The ambient VSM study proved the ferrimagnetism behavior of the CuFe2O4. TG/DTA was used to study the catalytic activity of the CuFe2O4 nanoparticles, the results revealed that a 78 °C reduction in the decomposition temperature of Ammonium Perchlorate (AP) was achieved while using 6% CuFe2O4 prepared using a mixed EA-AV and calcinated at 700 °C. Hence, CuFe2O4 can be potent catalytic agent in several environmental applications as an efficient catalyst